The <i>rpoa-2(op259)</i> mutation reduces irradiation-induced germ cell apoptosis but not cell cycle arrest response or DNA damage repair.

<p>A) DIC images of adult worms 24 hours after irradiation. Basal (physiologic) as well as DNA damage-induced germ cell death is confined to the late meiotic pachytene region of the germ line tubes; corpses are visible as cellularised, refractile discs (arrowheads). Size bar, 15 µm. B) Apoptotic cell corpses in the germ lines of X-ray treated adult hermaphrodites. Dashed lines represent basal levels (0 Gy), straight lines the levels following irradiation (60 Gy). At least three independent experiments (with n = 20 animals per condition) were performed with wild-type and <i>rpoa-2(op259)</i> worms, and one with animals mutant for the 9-1-1 complex subunit HUS-1. Error bars, standard deviation (SD) of corpse number per gonad over all experiments. C, D) In contrast to the DNA damage response mutant <i>hus-1(op241)</i>, cell cycle arrest is induced normally in <i>rpoa-2(op259)</i>. C) Percentage of mitotic cells with nuclear enlargement following IR. Error bars, SD from at least 12 gonads (approx. 40–50 total mitotic cells per gonad). D) Gonads were dissected from <i>opIs257[P_rad-54::rad-54::yfp 3′UTR; unc-119(+)]; unc-119(ed3)</i> or <i>rpoa-2(op259)</i>; <i>opIs257; unc-119(ed3)</i> adults, stained with Hoechst, and scored for YFP::RAD-54 foci. Size bar, 10 µm. E, F) A subset of rRNA processing and translation initiation mutants have reduced IR-induced apoptosis. Apoptotic response to IR irradiation in the gonads of the rRNA processing mutants <i>pro-2(na27)</i> and <i>pro-3(ar226)</i> (E) and of the eIF4E homolog mutants <i>ife-1(ok1978)</i> and <i>ife-2(ok306)</i> (F). Dashed lines, 0 Gy, straight lines, 60 Gy; error bars, SD of the number of germ cell corpses per gonad over at least 3 experiments (n = 20 animals per data point and experiment).